Diving equipment includes a so-called breathing regulator which is connected to one or more diving tanks or their technical equivalence and which is intended to adjust the tank pressure to a predetermined regulated pressure. The breathing regulator is provided with a valve device to this end. FIG. 1 illustrates diagrammatically one such valve device constructed in accordance with known technology. As will be seen, the valve includes an inlet side 11, which is under tank pressure Pinlet, and an outlet side 12, which is under the regulated pressure Poutlet. A conical valve body 14 is movable in a seating 15. The outlet side 12 is delimited by a flexible diaphragm or membrane 16, which is connected to a spring 17 that exerts a spring force Fspring on the diaphragm 16. Thus, one side of the diaphragm 16 is subjected to forces from the regulated pressure Poutlet, while the other side of the diaphragm is subjected to forces from the ambient pressure Pambient. The spring force, together, e.g., with forces exerted by the diaphragm 16, acts/act on a rod 18 connected to the valve body and thus exerting a force Frod onto said body.
This known valve has the following modus operandi. Movement of the valve body 14 is determined by the forces to which it is subjected. These forces include (as shown in the figure) an upwardly directed force Finlet determined by the tank pressure. This force is counteracted essentially by downwardly acting forces Foutlet, which are comprised generally of the effect of the regulated pressure Poutlet on the valve body and of the rod force Frod. When a diver who has a nozzle connected to the outlet side inhales, therewith causing a decrease in the regulated pressure, the pressure on the diaphragm 16 decreases and the diaphragm then exerts an increasing force on the rod 18. The force Frod then increases and, in the case of a functioning valve, the valve body will be moved downwards, thereby allowing tank gas to flow in through the seating 15 until the regulated pressure has increased to an extent at which the valve body returns to the position shown in FIG. 1.
One problem with such known valve devices is that movement of the valve body is dependent on the tank pressure, which in the case of a full tank can correspond to a super atmospheric pressure of about 300 bar and may fall to close on 0 bar during use. This means, in turn, that the valve characteristic will vary, together with the regulated pressure.
Several solutions to this problem have been proposed. One example of these proposed solutions is illustrated in FIG. 2. The valve shown in FIG. 2 corresponds to the valve shown in FIG. 1 in many aspects, although in this latter case the homogenous valve body 14 has been replaced with a valve body 14′ that includes a through-passing passageway 14a′. This passageway connects the outlet 12 with a space 19, which is sealed against the inlet 11 by means of an O-ring 20. Consequently, those forces Finlet acting on the valve body from the inlet side have essentially no axial component, thereby providing a balanced valve that gives a regulated pressure generally independent of Pinlet.
The use of a valve body of this design, however, has the drawback that the sealing surface between the valve body and the seating ultimately tends to leak. There are several reasons for this. The fit between the hole and the cone of the valve body must be perfect—no irregulatories can be permitted. After having been in use for a longer period of time, the cone becomes damaged, in the form of scratches and ruts in the hole-defining edge and the cone, this damage contributing to seal leakage. Furthermore, the valve body must be straight, meaning that the body must be guided with utmost precision. The O-ring may begin to leak as a result of abrasion and other type of wear, thereby preventing achievement of the desired balancing effect and sealing effect.
These drawbacks associated with the use of a conical valve body are avoided when using a spherical sealing body. A spherical body is self-guiding, thereby obviating the need of the accurate guide required by a conical valve body.
It will be realised, however, that the balancing solution illustrated in FIG. 2 cannot be applied when a spherical body is used as a valve-closing means.